Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing my newdesign; and,

FIG. 2 is the second image thereof.

The outermost perimeter illustrated by a pair of broken lines in thedrawings illustrates a display screen or portion thereof and forms nopart of the claimed design. The remaining broken lines in the drawingsillustrate portions of the graphical user interface that form no part ofthe claimed design.

The appearance of the transitional image sequentially transitionsbetween the images shown in FIGS. 1-2. The process or period in whichone image transitions to another image forms no part of the claimeddesign.

CLAIM The ornamental design for a display screen or portion thereof withtransitional graphical user interface, as shown and described.